The Piazza

Original D&D
From Men & Magic to Unearthed Arcana; OD&D & Holmes.
The Book-House: Find OD&D products.
Moderators: Idabrius, Blacky the Blackball

Classic D&D
Discuss B/X rules, BECMI rules, Rules Cyclopedia, and the crunchy bits from the gazetteers here.
The Book-House: Find Classic D&D (BECMI) products.
Moderators: Idabrius, Blacky the Blackball

AD&D 1st Edition
Discuss AD&D 1E here.
The Book-House: Find 1st Edition products.
Moderators: Idabrius, Blacky the Blackball

AD&D 2nd Edition
Published 1989.
The Book-House: Find 2nd Edition products.
Moderators: Idabrius, Blacky the Blackball

D&D 3rd Edition
Published 2000 & 2003.
The Book-House: Find 3.0 Edition products, Find 3.5 Edition products.
Moderators: Idabrius, Blacky the Blackball

D&D 4th Edition
Discuss 4th Edition rules, PoL setting concepts, and the GSL here.
The Book-House: Find 4th Edition products, Find D&D Essentials products.
Moderators: Idabrius, Blacky the Blackball

D&D 5th Edition
The next iteration of the Dungeons & Dragons game.
The Book-House: Find 5th Edition products.
Moderators: Idabrius, Blacky the Blackball

d20 Modern
It's a great new fantasy role-playing game. We pretend we're workers and students in an industrialised and technological society.
The Book-House: Find d20 Modern products.
Moderators: Idabrius, Blacky the Blackball

Pathfinder
Discuss Paizo's Pathfinder rules here. Discussion of the World of Golarion campaign setting can also be held here.
The Book-House: Find Pathfinder RPG products.
Moderators: Idabrius, Blacky the Blackball

Castles & Crusades
Discuss Troll Lord Game's rules set here.
Moderators: Idabrius, Blacky the Blackball

Dark Dungeons
Old School Revival at its best?
Moderators: Idabrius, Blacky the Blackball

Apotheon
Ashtagon's homebrew rules set.